Method :
* Preheat the oven 300 fahrenheit
1. Beat together the butter, margarine, and sugar until combined.
2. Add in the flour, cornstarch, and milk powder, beat again.
3. Beat in the yolk and vanilla.
4. Roll the dough until the thickness is about 1/2 inch.
5. Using flower cookie cutter, cut the dough. Repeat the method until all the dough is finish.
6. Put a small dollop of pineapple preserve into the centre of each cookie dough.
7. Brush the dough with yolk.
8. Bake for about 20-25 minutes or until the cookies become brown.
9. Let it cool and serve.